Method of Link Adaptation in Wireless Local Area Network and Apparatus for the Same

1. A method for link adaptation in a wireless local area network, the method comprising: receiving, by a responding device, a control frame from a requesting device, wherein the control frame is a first type frame or a second type frame, wherein the first type frame is a null data packet announcement (NDPA) frame carrying a request field, wherein the second type frame is a physical layer protocol data unit (PPDU) carrying the request field and a data field, wherein the request field is used for requesting feedback from the responding device, wherein the request field is set to ‘1’ when requesting the feedback, and wherein the NDPA frame includes an identifier identifying the responding device; estimating, by the responding device, a recommended feedback including a recommended modulation and coding scheme (MCS) by using a null data packet (NDP) frame received from the requesting device or the PPDU, wherein the NDP frame follows the NDPA frame, wherein if the control frame is the first type frame the recommended feedback is estimated by using the NDP frame, wherein if the control frame is the second type frame the recommended feedback is estimated by using a group ID and a number of spatial streams used for the PPDU; configuring, by the responding device, a first feedback frame including the recommended feedback; and transmitting, by the responding device, the first feedback frame.

2. The method of claim 1 , wherein the control frame is broadcast to the responding device.

3. The method of claim 2 , further comprising: receiving, by the responding device, a feedback poll frame to the requesting device after transmitting the first feedback frame; and transmitting, by the responding device, a second feedback frame to the requesting device.

4. The method of claim 1 , wherein the requesting device is an access point.

5. A wireless device configured for link adaptation in a wireless local area network, the wireless device comprising: a transceiver configured to transmit and receive radio signals; and a processor operably coupled to the transceiver and configured to: receive, via the transceiver, a control frame from a requesting device, wherein the control frame is a first type frame or a second type frame, wherein the first type frame is a null data packet announcement (NDPA) frame carrying a request field and a data field, wherein the second type frame is a physical layer protocol data unit (PPDU) carrying the request field, wherein the request field is used for requesting feedback from the responding device, wherein the request field is set to ‘1’ when requesting the feedback, and wherein the NDPA frame includes an identifier identifying the responding device, estimate a recommended feedback including a recommended modulation and coding scheme (MCS) by using a null data packet (NDP) frame received from the requesting device or the PPDU, wherein the NDP frame follows the NDPA frame, wherein if the control frame is the first type frame the recommended feedback is estimated by using the NDP frame, wherein if the control frame is the second type frame the recommended feedback is estimated by using a group ID and a number of spatial streams used for the PPDU, configure a first feedback frame as a response to the NDPA frame including the recommended feedback, and transmit, via the transceiver, the first feedback frame.

6. The wireless device of claim 5 , wherein the control frame is broadcast to the responding device.

7. The wireless device of claim 6 , wherein the processor is further configured to: receive a feedback poll frame to the requesting device after transmitting the first feedback frame, and transmit a second feedback frame to the requesting device.